Electronic component and coil component

ABSTRACT

In an electronic component, a terminal electrode has a thickest portion and a part thinner than the thickest portion. Accordingly, an increase in solder fillet forming region occurs when the electronic component is solder-mounted onto a predetermined mounting substrate. In the electronic component, mounting strength is improved as a result of the increase in solder fillet forming region. In addition, in the electronic component, the thickest portion overlaps a bump electrode in a direction orthogonal to the lower surface of an element body. Accordingly, the impact that is applied to the electronic component during the mounting onto the mounting substrate is reduced and the impact resistance of the electronic component is improved.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a Division of application Ser. No. 16/811,610 filed Mar. 6,2020, which claims the benefit of priority from Japanese PatentApplications No. 2019-50780, No. 2019-50781, and No. 2019-50782, filedon 19 Mar., 2019, the entire contents of which are incorporated hereinby reference.

TECHNICAL FIELD

The present disclosure relates to an electronic component and a coilcomponent.

BACKGROUND

In recent years, development of a bottom surface terminal-type coilcomponent (a type of electronic component) in which a terminal electrodeis provided only on the bottom surface of a chip has been promoted sothat high-density mounting is coped with. Japanese Unexamined PatentPublication No. 2017-528001 (Patent Literature 1) discloses a bottomsurface terminal-type electronic component provided with a substrateextending in parallel to a bottom surface provided with a terminalelectrode, in which coil patterns are formed on both surfaces of thesubstrate.

SUMMARY Technical Problem

The inventors have conducted research on the structure of the bottomsurface of an electronic component. As a result, the inventors havenewly found a technique with which impact resistance can be improvedwhile the mounting strength of the electronic component during mountingonto on a mounting substrate is improved.

Provided according to the present disclosure is an electronic componentand a coil component with which impact resistance can be improved alongwith mounting strength.

Solution to Problem

An electronic component according to an aspect of the present disclosureincludes an element body having a lower surface configured to face amounting substrate, an inner conductor disposed in the element body andhaving a first end portion and a second end portion, a pair of terminalelectrodes provided on the lower surface of the element body, and a pairof bump electrodes extending in a direction intersecting with the lowersurface of the element body and respectively interconnecting the firstand second end portions of the inner conductor and the pair of terminalelectrodes. The terminal electrode has a thickest portion where athickness with respect to the lower surface of the element body islargest and a part thinner than the thickest portion and the thickestportion overlaps the bump electrode in a direction orthogonal to thelower surface.

In the electronic component described above, the terminal electrode hasthe thickest portion and the part thinner than the thickest portion.Accordingly, an increase in solder fillet forming region occurs when acoil component is solder-mounted onto a predetermined mountingsubstrate. Mounting strength is improved as a result of the increase insolder fillet forming region. In addition, in the electronic componentdescribed above, the thickest portion overlaps the bump electrode in thedirection orthogonal to the lower surface. Accordingly, the impact thatis applied to the electronic component during the mounting onto themounting substrate is reduced and the impact resistance of theelectronic component is improved.

The electronic component according to another aspect further includes arecess portion provided in the lower surface and positioned between thepair of terminal electrodes. A part of the terminal electrode isprovided in the recess portion.

In the electronic component according to another aspect, the recessportion has a slope inclined with respect to the lower surface and iscontinuous with the lower surface on the slope.

In the electronic component according to another aspect, the bumpelectrode has an enlarged portion and a cross-sectional dimension of theenlarged portion in a plane orthogonal to the lower surface graduallyincreases toward the lower surface of the element body.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view illustrating a coil componentaccording to an embodiment.

FIG. 2 is a cross-sectional view of the coil component taken along lineII-II in FIG. 1 .

FIG. 3 is a plan view illustrating a substrate of the coil componentillustrated in FIG. 1 .

FIG. 4 is a cross-sectional view of the coil component taken along lineIV-IV in FIG. 1 .

FIG. 5 is a cross-sectional view of the coil component taken along lineV-V in FIG. 1 .

FIG. 6 is a cross-sectional view of the coil component taken along lineVI-VI in FIG. 1 .

FIG. 7 is a cross-sectional view of the coil component taken along lineVII-VII in FIG. 1 .

FIG. 8 is a diagram illustrating a positional relationship between bumpelectrodes.

FIGS. 9A to 9C are diagrams illustrating processes of a method formanufacturing the coil component illustrated in FIG. 1 .

FIGS. 10A to 10C are diagrams illustrating processes of the method formanufacturing the coil component illustrated in FIG. 1 .

FIGS. 11A to 11C are diagrams illustrating processes of the method formanufacturing the coil component illustrated in FIG. 1 .

DETAILED DESCRIPTION

Hereinafter, various embodiments and examples will be described withreference to the drawings. The same or corresponding parts will bedenoted by the same reference numerals in the drawings and redundantdescription will be omitted.

A coil component 1 as a type of electronic component will be describedin the present embodiment. As illustrated in FIG. 1 , the coil component1 according to the embodiment has a rectangular parallelepiped outershape. The coil component 1 can be designed so as to have, for example,a long side dimension of 1.2 mm, a short side dimension of 1.0 mm, and aheight dimension of 0.5 mm. Alternatively, as another example, the coilcomponent 1 can be designed so as to have a long side dimension of 2.0mm, a short side dimension of 1.2 mm, and a height dimension of 0.6 mm.

The coil component 1 is configured to be provided with an element body10 and a coil portion 20 embedded in the element body 10.

The element body 10 has a rectangular parallelepiped outer shape and hassix surfaces 10 a to 10 f. As for the surfaces 10 a to 10 f of theelement body 10, the upper surface 10 a and the lower surface 10 b areparallel to each other, the end surfaces 10 c and 10 d are parallel toeach other, and the side surfaces 10 e and 10 f are parallel to eachother. The lower surface 10 b of the element body 10 faces a mountingsurface of a mounting substrate onto which the coil component 1 ismounted in parallel to the mounting surface.

A magnetic material constitutes the element body 10. In the presentembodiment, a metal magnetic powder-containing resin as a type ofmagnetic material constitutes the element body 10. The metal magneticpowder-containing resin is binder powder in which metal magnetic powderis bound by a binder resin. The metal magnetic powder can be made of,for example, an iron-nickel alloy (permalloy alloy), carbonyl iron, anamorphous, non-crystalline, or crystalline FeSiCr-based alloy, sendust,or the like. The binder resin is, for example, a thermosetting epoxyresin. In the present embodiment, the content of the metal magneticpowder in the binder powder is 80 to 92 vol % in volume percent and 95to 99 wt % in mass percent. From the viewpoint of magnetic properties,the content of the metal magnetic powder in the binder powder may be 85to 92 vol % in volume percent and 97 to 99 wt % in mass percent.

The coil portion 20 is configured to be provided with a first coil body30, a substrate 40, and a second coil body 50. Specifically, the firstcoil body 30 is provided on an upper surface 40 a of the substrate 40positioned on the upper surface side of the element body 10 and thesecond coil body 50 is provided on a lower surface 40 b of the substrate40 positioned on the lower surface side of the element body 10. In thepresent embodiment, the pattern shape of the first coil body 30 viewedfrom the upper surface 40 a side of the substrate 40 is the same as thepattern shape of the second coil body 50 viewed from the lower surface40 b side of the substrate 40.

The substrate 40 is a plate-shaped member extending in parallel to theupper surface 10 a and the lower surface 10 b of the element body 10.The substrate 40 is disposed such that the distance between thesubstrate 40 and the lower surface 10 b of the element body 10 isshorter than the distance between the substrate 40 and the upper surface10 a of the element body 10. As illustrated in FIG. 3 , the substrate 40has an elliptical ring-shaped coil forming portion 41 extending alongthe long side direction of the element body 10, a pair of projectionportions 46A and 46B respectively extending from the coil formingportion 41 to the side surfaces 10 e and 10 f of the element body 10,and a pair of frame portions 47A and 47B extending along the short sidedirection of the element body 10 and sandwiching the coil formingportion 41 from both sides. The substrate 40 is provided withsubstantially triangular through holes 43 and 44 in the regions that aredefined by the outer periphery of the coil forming portion 41 and thepair of frame portions 47A and 47B, respectively. In addition, the coilforming portion 41 is provided with a circular through hole 45 in anedge portion of an oval opening 42.

A substrate with a plate thickness of 60 μm in which a glass cloth isimpregnated with cyanate resin (Bismaleimide Triazine (BT) resin:registered trademark) can be used as the substrate 40. Polyimide,aramid, and so on can be used besides the BT resin. Ceramic or glass canalso be used as a material of the substrate 40. A material of thesubstrate 40 may be a mass-produced printed board material.Particularly, a material of the substrate 40 may be a resin materialused for a BT printed board, an FR4 printed board, or an FR5 printedboard.

The first coil body 30 is provided on the upper surface 40 a of thesubstrate 40 in the coil forming portion 41. As illustrated in FIG. 2 ,the first coil body 30 is configured to be provided with a first planarcoil 32 constituting a part of a coil 22 (inner conductor) of the coilcomponent 1, a first insulator 34, and a first island-shaped electrode36.

The first planar coil 32 is a substantially oval spiral air core coilwound around the opening 42 of the coil forming portion 41 in the samelayer on the upper surface 40 a of the substrate 40. The number of turnsof the first planar coil 32 may be one or a plurality of turns. In thepresent embodiment, the number of turns of the first planar coil 32 isthree to four. The first planar coil 32 has an outside end portion 32 a(first extracting end portion), an inside end portion 32 b (firstconnection end portion), and a first turn portion 32 c interconnectingthe outside end portion 32 a and the inside end portion 32 b. Theoutside end portion 32 a is provided in the region that covers thethrough hole 43 of the substrate 40 when viewed from the thicknessdirection of the substrate 40 and has a substantially triangular shape.More specifically, the outside end portion 32 a has a rounded triangularshape. Even more specifically, the side surface on the inner peripheralside of the outside end portion 32 a faces the first turn portion 32 cand is curved in a circular arc shape so as to be along the outerperipheral surface of the first turn portion 32 c. The inside endportion 32 b is provided in the region that covers the through hole 45of the substrate 40 when viewed from the thickness direction of thesubstrate 40 and has a circular shape. The first planar coil 32 is madeof, for example, Cu and can be formed by electrolytic plating.

The first island-shaped electrode 36 is provided in the region thatoverlaps the through hole 44 of the substrate 40 when viewed from thethickness direction of the substrate 40 and has a substantiallytriangular shape. More specifically, the first island-shaped electrode36 has a rounded triangular shape. Even more specifically, the sidesurface on the inner peripheral side of the first island-shapedelectrode 36 faces the first turn portion 32 c and is curved in acircular arc shape so as to be along the outer peripheral surface of thefirst turn portion 32 c. The first island-shaped electrode 36 is not incontact with the first planar coil 32 on the upper surface 40 a of thesubstrate 40. The first island-shaped electrode 36 is a dummy electrodethat is not necessary for constituting the circuit of the coil portion20. The first island-shaped electrode 36 is made of, for example, Cu andcan be formed by electrolytic plating.

The first insulator 34 is provided on the upper surface 40 a of thesubstrate 40 and is a thick film resist patterned by knownphotolithography. The first insulator 34 defines the growth region ofthe first planar coil 32 and the first island-shaped electrode 36 andcovers the first planar coil 32 in the same layer as the layer where thefirst planar coil 32 is formed. In the present embodiment, the firstinsulator 34 includes an outer wall 34 a and an inner wall 34 b definingthe contour of the first planar coil 32, a partition wall 34 cseparating the inside and outside turns of the first turn portion 32 cof the first planar coil 32, and an outer wall 34 d defining the contourof the first island-shaped electrode 36. The first insulator 34 is madeof, for example, an epoxy resin.

As illustrated in FIG. 5 , the first coil body 30 further includes aprotective film 38 integrally covering the first planar coil 32 and thefirst insulator 34 from the upper surface 10 a side of the element body10. The protective film 38 is made of, for example, an epoxy resin. Theprotective film 38 enhances the insulation between the first planar coil32 and the metal magnetic powder contained in the element body 10.

The second coil body 50 is provided on the lower surface 40 b of thesubstrate 40 in the coil forming portion 41. As illustrated in FIG. 4 ,the second coil body 50 is configured to be provided with a secondplanar coil 52 constituting a part of the coil 22 of the coil component1, a second insulator 54, and a second island-shaped electrode 56.

The second planar coil 52 is a substantially oval spiral air core coilwound around the opening 42 of the coil forming portion 41 in the samelayer on the lower surface 40 b of the substrate 40. The number of turnsof the second planar coil 52 may be one or a plurality of turns. In thepresent embodiment, the number of turns of the second planar coil 52 isthree to four. The second planar coil 52 has an outside end portion 52 a(second extracting end portion), an inside end portion 52 b (secondconnection end portion), and a second turn portion 52 c interconnectingthe outside end portion 52 a and the inside end portion 52 b. Theoutside end portion 52 a is provided in the region that covers thethrough hole 44 of the substrate 40 when viewed from the thicknessdirection of the substrate 40 and has a substantially triangular shapesimilarly to the outside end portion 32 a of the first planar coil 32.In other words, the outside end portion 52 a has a rounded triangularshape and the side surface on the inner peripheral side of the outsideend portion 52 a that faces the second turn portion 52 c is curved in acircular arc shape so as to be along the outer peripheral surface of thesecond turn portion 52 c. The inside end portion 52 b is provided in theregion that covers the through hole 45 of the substrate 40 when viewedfrom the thickness direction of the substrate 40 and has a circularshape. The second planar coil 52 is made of, for example, Cu and can beformed by electrolytic plating.

The second island-shaped electrode 56 is provided in the region thatoverlaps the through hole 43 of the substrate 40 when viewed from thethickness direction of the substrate 40 and has a substantiallytriangular shape similarly to the first island-shaped electrode 36. Inother words, the second island-shaped electrode 56 has a roundedtriangular shape and the side surface on the inner peripheral side ofthe second island-shaped electrode 56 that faces the second turn portion52 c is curved in a circular arc shape so as to be along the outerperipheral surface of the second turn portion 52 c. The secondisland-shaped electrode 56 is not in contact with the second planar coil52 on the lower surface 40 b of the substrate 40. The secondisland-shaped electrode 56 is made of, for example, Cu and can be formedby electrolytic plating.

The second insulator 54 is provided on the lower surface 40 b of thesubstrate 40 and is a thick film resist patterned by knownphotolithography. The second insulator 54 defines the growth region ofthe second planar coil 52 and the second island-shaped electrode 56 andcovers the second planar coil 52 in the same layer as the layer wherethe second planar coil 52 is formed. In the present embodiment, thesecond insulator 54 includes an outer wall 54 a and an inner wall 54 bdefining the contour of the second planar coil 52, a partition wall 54 cseparating the inside and outside turns of the second turn portion 52 cof the second planar coil 52, and an outer wall 54 d defining thecontour of the second island-shaped electrode 56. The second insulator54 is made of, for example, an epoxy resin.

As illustrated in FIG. 5 , the second coil body 50 further includes aprotective film 58 integrally covering the second planar coil 52 and thesecond insulator 54 from the lower surface 10 b side of the element body10. The protective film 58 is made of, for example, an epoxy resin. Theprotective film 58 enhances the insulation between the second planarcoil 52 and the metal magnetic powder contained in the element body 10.

A conductor 53 connected to the second island-shaped electrode 56 isprovided on the lower surface 40 b of the substrate 40. As describedlater, the conductor 53 functions as an electric power supply line whenthe coil 22 is formed by electrolytic plating. The conductor 53 isprovided so as to straddle the coil forming portion 41 and the frameportion 47B. As illustrated in FIG. 1 , the conductor 53 is exposed fromthe end surface 10 c of the element body 10. The conductor 53 iselectrically connected to the first planar coil 32 and the second planarcoil 52 via the second island-shaped electrode 56.

As illustrated in FIG. 6 , the through hole 45 of the substrate 40 isfilled with a via conductor 48. The respective inside end portions 32 band 52 b of the first planar coil 32 provided on the upper surface 40 aof the substrate 40 and the second planar coil 52 provided on the lowersurface 40 b of the substrate 40 are interconnected via the viaconductor 48 in the through hole 45 penetrating the substrate 40 in thethickness direction. In the present embodiment, the first planar coil32, the second planar coil 52, and the via conductor 48 constitute theair core coil 22 around the opening 42 of the substrate 40. The coil 22has a coil axis parallel to the thickness direction of the substrate 40(that is, the direction in which the upper surface 10 a and the lowersurface 10 b face each other).

The first planar coil 32 and the second planar coil 52 are wound suchthat electric currents flow in the same direction (that is, the samecircumferential direction when the substrate 40 is viewed from thethickness direction) when a voltage is applied between both end portionsof the coil 22 (that is, the outside end portion 32 a of the firstplanar coil 32 and the outside end portion 52 a of the second planarcoil 52). In the present embodiment, the first planar coil 32 has aclockwise circumferential direction from the outside end portion 32 a tothe inside end portion 32 b as illustrated in FIG. 2 and the secondplanar coil 52 has a clockwise circumferential direction from the insideend portion 52 b to the outside end portion 52 a as illustrated in FIG.4 . Electric currents flow in the same direction through the firstplanar coil 32 and the second planar coil 52, and thus generatedmagnetic fluxes are superposed and reinforce each other. The coil 22 iscovered with the first insulator 34, the second insulator 54, and theprotective films 38 and 58, which are the first insulating coatings ofthe present disclosure. As a result, insulation is achieved between thecoil 22 and the element body 10.

As illustrated in FIG. 7 , the through holes 43 and 44 of the substrate40 are filled with a via conductor 49. The first island-shaped electrode36 provided on the upper surface 40 a of the substrate 40 and theoutside end portion 52 a of the second planar coil 52 provided on thelower surface 40 b of the substrate 40 are interconnected via the viaconductor 49 in the through hole 43 penetrating the substrate 40 in thethickness direction. Likewise, the outside end portion 32 a of the firstplanar coil 32 provided on the upper surface 40 a of the substrate 40and the second island-shaped electrode 56 provided on the lower surface40 b of the substrate 40 are interconnected via the via conductor 49 inthe through hole 44 penetrating the substrate 40 in the thicknessdirection.

In the element body 10, a pair of bump electrodes 60 are embedded inaddition to the coil portion 20. The pair of bump electrodes 60 extendalong the thickness direction of the substrate 40 such that both endportions of the coil 22 are extracted to the lower surface 10 b of theelement body 10. A bump electrode 60A, which is one of the pair of bumpelectrodes 60 and connected to one end portion 32 a (first end portion)of the coil 22, extends from the lower surface of the secondisland-shaped electrode 56 to the lower surface 10 b of the element body10 and is electrically connected to one end portion 32 a of the coil 22via the second island-shaped electrode 56. A bump electrode 60B, whichis the other bump electrode 60 and connected to the other end portion 52a of the coil 22, is in direct contact with the other end portion 52 a(second end portion) of the coil 22 and extends from the lower surfaceof the other end portion 52 a of the coil 22 to the lower surface 10 bof the element body 10.

As illustrated in FIG. 8 , each of the pair of bump electrodes 60 ispositioned in a corner portion of a rectangular region 24 including thefirst coil body 30 and the second coil body 50 when viewed from thethickness direction of the substrate 40. The one-dot chain line in FIG.8 is a virtual line indicating the rectangular region 24. In the presentembodiment, the rectangular region 24 circumscribes the first coil body30 and the second coil body 50 when viewed from the thickness directionof the substrate 40. Each bump electrode 60 has a substantiallytriangular cross-sectional shape in a plane orthogonal to the thicknessdirection of the substrate 40. More specifically, the cross-sectionalshape of each bump electrode 60 is a triangular shape along the outerperiphery of the first coil body 30 or the second coil body 50 and twosides defining a corner portion of the rectangular region 24. Forexample, the bump electrode 60A has a substantially triangularcross-sectional shape along two sides defining a corner portion of therectangular region 24 and the outer periphery of the second coil body 50and the bump electrode 60B has a substantially triangularcross-sectional shape along two sides defining a corner portion of therectangular region 24 and the outer periphery of the first coil body 30.

Each of the bump electrodes 60A and 60B may have the samecross-sectional shape and the same cross-sectional dimension over theentire length of the substrate 40 in the thickness direction. In thepresent embodiment, each of the bump electrodes 60A and 60B has anenlarged portion 60 a at the lower end that is a part near the lowersurface 10 b of the element body 10. In the enlarged portion 60 a, thecross-sectional dimension (specifically, the cross-sectional dimensionin the plane orthogonal to the thickness direction of the substrate 40)gradually increases toward the lower surface 10 b of the element body10.

The periphery of each of the bump electrodes 60A and 60B may be coveredwith an insulator 62 (second insulating coating) over the entire lengthof the substrate 40 in the thickness direction. The insulator 62 may bemade of, for example, an epoxy resin. In the present embodiment, theenlarged portion 60 a of each of the bump electrodes 60A and 60B is notcovered with the insulator 62 and is exposed from the insulator 62. Theinsulator 62 is provided separately from the second insulator 54.

Neither of the bump electrodes 60 overlaps the first turn portion 32 cof the first planar coil 32 in the thickness direction of the substrate40 and neither of the bump electrodes 60 overlaps the second turnportion 52 c of the second planar coil 52 in the thickness direction ofthe substrate 40. More specifically, as for each bump electrode 60, atleast the end portion on the substrate 40 side (that is, the upper endportion) overlaps neither the first turn portion 32 c nor the secondturn portion 52 c. In the present embodiment, the enlarged portion 60 aat the lower end of the bump electrode 60 also overlaps neither thefirst turn portion 32 c nor the second turn portion 52 c in thethickness direction of the substrate 40. In an alternative aspect, thelower end portion of the bump electrode 60 may overlap the first turnportion 32 c and the second turn portion 52 c in the thickness directionof the substrate 40.

The through holes 43 and 44 and the via conductor 49 are positioned incorner portions of the rectangular region 24 similarly to the pair ofbump electrodes 60. The cross-sectional shape of the via conductor 49(that is, the opening shape of the through holes 43 and 44) is asubstantially triangular shape along the outer periphery of the firstcoil body 30 or the second coil body 50 and two sides defining a cornerportion of the rectangular region 24 similarly to the cross-sectionalshape of the pair of bump electrodes 60. The cross-sectional shape ofthe via conductor 49 may be identical or similar to the cross-sectionalshape of the bump electrode 60.

Similarly to the through holes 43 and 44, the outside end portion 32 aof the first planar coil 32 overlapping the through hole 43 and theoutside end portion 52 a of the second planar coil 52 overlapping thethrough hole 44 are positioned in corner portions of the rectangularregion 24.

Similarly to the pair of bump electrodes 60, the first island-shapedelectrode 36 and the second island-shaped electrode 56 are positioned incorner portions of the rectangular region 24. The cross-sectional shapeof the first island-shaped electrode 36 and the second island-shapedelectrode 56 in the plane orthogonal to the thickness direction of thesubstrate 40 is a substantially triangular shape along the outerperiphery of the first coil body 30 or the second coil body 50 and twosides defining a corner portion of the rectangular region 24. Thecross-sectional shape of the first island-shaped electrode 36 and thesecond island-shaped electrode 56 may be identical or similar to thecross-sectional shape of the bump electrode 60.

The lower surface 10 b of the element body 10 is provided with a recessportion 12 as illustrated in FIGS. 5 and 7 . The recess portion 12 is apart recessed one step with respect to the lower surface 10 b. Therecess portion 12 has a slope 12 a inclined with respect to the lowersurface 10 b and is continuous with the lower surface 10 b on the slope12 a.

The lower surface 10 b of the element body 10 is provided with a pair ofterminal electrodes 70. The pair of terminal electrodes 70 arerespectively connected to the pair of bump electrodes 60 exposed fromthe lower surface 10 b of the element body 10. A terminal electrode 70A,which is one of the pair of terminal electrodes 70 and connected to thebump electrode 60A, is provided on the lower surface 10 b near the endsurface 10 c. A terminal electrode 70B, which is the other terminalelectrode 70 and connected to the bump electrode 60B, is provided on thelower surface 10 b near the end surface 10 d. The lower end of each bumpelectrode 60 is the enlarged portion 60 a, and thus the contact areabetween the bump electrode 60 and the terminal electrode 70 isincreased. A resin electrode constitutes each of the terminal electrodes70A and 70B and each of the terminal electrodes 70A and 70B can be madeof, for example, a resin containing Ag powder.

A part of each of the terminal electrodes 70A and 70B is provided in therecess portion 12. In other words, a part of the terminal electrode 70Aand a part of the terminal electrode 70B reach the slope 12 a of therecess portion 12 from the vicinity of the end surface 10 c and thevicinity of the end surface 10 d. Accordingly, a length W1 of theterminal electrode 70A in the direction in which the end surfaces 10 cand 10 d face each other and a length W2 of the terminal electrode 70Bin the direction in which the end surfaces 10 c and 10 d face each otherare longer than in a case where a part of each of the terminalelectrodes 70A and 70B does not reach the slope 12 a of the recessportion 12. The length W1 of the terminal electrode 70A and the lengthW2 of the terminal electrode 70B may or may not be equal to each other.In addition, extension between the terminal electrodes 70A and 70B onthe lower surface 10 b is achieved by the slope 12 a of the recessportion 12, and thus a separation distance W3 between the terminalelectrodes 70A and 70B does not decrease much even when a part of eachof the terminal electrodes 70A and 70B reaches the slope 12 a of therecess portion 12. Accordingly, insulation is sufficiently achievedbetween the terminal electrodes 70A and 70B.

A thickness d of each of the terminal electrodes 70A and 70B withrespect to the lower surface 10 b is not uniform in the region thatcorresponds to the bump electrode 60. In other words, each of theterminal electrodes 70A and 70B has a thickest portion P where thethickness d is largest and a part thinner than the thickest portion P.In the terminal electrodes 70A and 70B according to the presentembodiment, the thickest portion P is present at the position thatoverlaps the bump electrode 60 in the thickness direction of thesubstrate 40 and the thickness d decreases as the distance from thethickest portion P increases. Since the thickness d of each of theterminal electrodes 70A and 70B is not uniform, an increase in solderfillet forming region occurs when the coil component 1 is solder-mountedonto a predetermined mounting substrate such that the lower surface 10 bof the element body 10 and the mounting substrate face each other.Mounting strength is improved as a result.

Hereinafter, a procedure for manufacturing the coil component 1described above will be described with reference to FIGS. 9A to 9C, 10Ato 10C, and 11A to 11C.

The substrate 40 is prepared as illustrated in FIG. 9A when the coilcomponent 1 is manufactured. At this time, the substrate 40 is formed ona wafer and a plurality of the substrates 40 are arranged in a matrixform on the wafer. A seed pattern S is formed on both surfaces 40 a and40 b of the substrate 40. The seed pattern S includes patternsrespectively corresponding to the first planar coil 32, the firstisland-shaped electrode 36, the second planar coil 52, and the secondisland-shaped electrode 56. In addition, the conductor 53 connected tothe pattern corresponding to the second island-shaped electrode 56 andconnected to an electric power source (not illustrated) is provided onthe lower surface 40 b of the substrate 40. Further, the through holes43, 44, and 45 described above are provided in the substrate 40 and thethrough holes 43, 44, and 45 are respectively filled with the viaconductors 48 and 49. The through holes 43, 44, and 45 and the viaconductors 48 and 49 are not illustrated in FIG. 9A.

The first insulator 34 and the second insulator 54 are subsequentlyformed on both surfaces 40 a and 40 b of the substrate 40 as illustratedin FIG. 9B. The first insulator 34 and the second insulator 54 can beformed by a thick film resist being patterned by known photolithography.The first insulator 34 is formed so as to surround the seed pattern Scorresponding to the first planar coil 32 and the first island-shapedelectrode 36 and the second insulator 54 is formed so as to surround theseed pattern S corresponding to the second planar coil 52 and the secondisland-shaped electrode 56.

Next, as illustrated in FIG. 9C, the first planar coil 32, the firstisland-shaped electrode 36, the second planar coil 52, and the secondisland-shaped electrode 56 are respectively formed by electrolyticplating of Cu being performed while electric power is supplied from theconductor 53 to a seed pattern 51. At this time, the space defined bythe first insulator 34 and the second insulator 54 is filled with Cu. Ifnecessary, a surface treatment (such as a blackening treatment) can beperformed on the Cu exposed from the insulator after the electrolyticplating. A blackening layer (Cu oxide layer) is formed on the Cu platingduring the blackening treatment. By the surface-roughened blackeninglayer being formed, the Cu plating and the protective films 38 and 58are firmly joined by an anchor effect.

The conductor 53 may be electrically connected to one or both of thefirst planar coil 32 and the second planar coil 52 insofar as theconductor 53 can be used for electrolytic plating of the first planarcoil 32 and the second planar coil 52. In the present embodiment, theconductor 53 is exposed from the surface of the element body 10 (thatis, the end surface 10 c). Accordingly, it is possible to determine theposition of the bump electrode 60A or the position of the secondisland-shaped electrode 56 to which the conductor 53 is connected byconfirming the position where the conductor 53 is exposed from theappearance of the coil component 1.

The protective films 38 and 58 described above are subsequently formedas illustrated in FIG. 10A. The second island-shaped electrode 56 andthe outside end portion 52 a of the second planar coil 52 where the bumpelectrode 60 is formed are exposed from the protective film 58 in partor in whole without the protective film 58 being formed (or with theprotective film 58 removed after formation). In a case where theblackening treatment described above is performed, the blackening layeron the second island-shaped electrode 56 and the outside end portion 52a of the second planar coil 52 in the region exposed from the protectivefilm 58 is removed by a reduction treatment. The coil portion 20described above is obtained through the process described above.

Subsequently, as illustrated in FIG. 10B, the tubular insulators 62respectively surrounding the regions where the pair of bump electrodes60 are formed (that is, the second island-shaped electrode 56 and theoutside end portion 52 a of the second planar coil 52) are formed. Theinsulator 62 can be formed by the thick film resist that is provided onthe lower surface 40 b side of the substrate 40 being patterned by knownphotolithography.

Subsequently, as illustrated in FIG. 10B, a resist 80 is formed on thelower surface 40 b side of the substrate 40. The resist 80 has anopening 82 corresponding to the opening 42 of the substrate 40. Inaddition, the resist 80 has openings 84A and 84B respectivelycorresponding to the regions where the pair of bump electrodes 60 areformed (that is, the second island-shaped electrode 56 and the outsideend portion 52 a of the second planar coil 52).

Further, as illustrated in FIG. 10C, electrolytic plating of Cu isperformed by means of the second island-shaped electrode 56 and theoutside end portion 52 a of the second planar coil 52 exposed from theprotective film 58 inside the insulator 62. At this time, the internalspace of the insulator 62 is filled with Cu and the bump electrodes 60are respectively formed in the insulators 62.

Subsequently, the element body 10 is configured by the coil portion 20and the bump electrode 60 being integrally covered with a magneticmaterial by a known method. The recess portion 12 of the lower surface10 b of the element body 10 can be provided by the flat lower surface 10b being polished by means of a grinder or the like. Lastly, themanufacturing of the coil component 1 is completed by the terminalelectrode 70 that has the above-described shape being formed on thelower surface 10 b of the element body 10 and the wafer being dividedinto individual pieces. In the coil component 1, the resist that is usedfor the planar coils 32 and 52 to be formed remains as the firstinsulator 34 and the second insulator 54. The first insulator 34 and thesecond insulator 54 are so-called permanent resists.

The insulator 62 can also be formed by the following method. In otherwords, as illustrated in FIG. 11A, the thick-film resist 80 is formed onthe lower surface 40 b side of the substrate 40. The resist 80 has theopening 82 corresponding to the opening 42 of the substrate 40. Inaddition, the resist 80 has the openings 84A and 84B respectivelycorresponding to the regions where the pair of bump electrodes 60 areformed (that is, the second island-shaped electrode 56 and the outsideend portion 52 a of the second planar coil 52). Subsequently, asillustrated in FIG. 11B, electrolytic plating of Cu is performed bymeans of the second island-shaped electrode 56 and the outside endportion 52 a of the second planar coil 52 exposed from the protectivefilm 58 in the openings 84A and 84B of the resist 80. At this time, theinternal spaces of the openings 84A and 84B are filled with Cu and thebump electrodes 60 are respectively formed in the openings 84A and 84B.Further, as illustrated in FIG. 11C, the bump electrode 60 is exposed bythe resist 80 being removed. Subsequently, uncured resin (such as epoxyresin) is applied by dipping or the like to the surface of the bumpelectrode 60 that is exposed, curing is performed, and the entiresurface is covered with an insulator. Further, the insulator that coversthe end surface of the bump electrode 60 (surface on the lower surface10 b side of the element body 10) is selectively removed by polishing orthe like.

The tubular insulator 62 covering the periphery of the bump electrode 60is obtained as a result.

As described above, in the coil component 1, the terminal electrode 70has the thickest portion P and the part thinner than the thickestportion P. Accordingly, an increase in solder fillet forming regionoccurs when the coil component 1 is solder-mounted onto a predeterminedmounting substrate. In the coil component 1, mounting strength isimproved as a result of the increase in solder fillet forming region. Inaddition, in the coil component 1, the thickest portion P overlaps thebump electrode 60 in a direction orthogonal to the lower surface 10 b ofthe element body 10. Accordingly, the impact that is applied to the coilcomponent 1 during the mounting onto the mounting substrate is reducedand the impact resistance of the coil component 1 is improved.

In addition, in the coil component 1, a part of each of the terminalelectrodes 70A and 70B is provided in the recess portion 12.

Accordingly, the length W1 of the terminal electrode 70A in thedirection in which the end surfaces 10 c and 10 d face each other andthe length W2 of the terminal electrode 70B in the direction in whichthe end surfaces 10 c and 10 d face each other are longer than in a casewhere a part of each of the terminal electrodes 70A and 70B does notreach the slope 12 a of the recess portion 12 and insulation issufficiently achieved between the terminal electrodes 70A and 70B.

Further, in the coil component 1, the first coil body 30 is providedwith the first island-shaped electrode 36 as a dummy electrode.Accordingly, the pattern shape of the first coil body 30 and the patternshape of the second coil body 50 provided with the second island-shapedelectrode 56 are uniform. As a result, when the first coil body 30 andthe second coil body 50 are simultaneously formed by plating on bothsurfaces of the substrate 40, a discrepancy in plating growth ratebetween the two coil bodies 30 and 50 is suppressed and the coil bodies30 and 50 are capable of achieving plating growth at the same rate.

Here, Patent Literature 1 discloses a bottom surface terminal-type coilcomponent in which a metal magnetic powder-containing resin constitutesan element body. In addition, FIG. 21 of Patent Literature 1 discloses abump electrode extending from an end portion of a coil toward a terminalelectrode provided on a chip bottom surface. The inventors have studiedbump electrode insulation. As a result, the inventors have newly found atechnique with which insulation can be enhanced between the bumpelectrode and the element body made of the metal magneticpowder-containing resin.

A coil component according to an aspect of the present disclosureincludes an element body made of a metal magnetic powder-containingresin and having a lower surface facing a mounting substrate, a coildisposed in the element body and covered with a first insulatingcoating, a pair of terminal electrodes provided on the lower surface ofthe element body, a pair of bump electrodes extending in a directionintersecting with the lower surface of the element body and respectivelyinterconnecting both end portions of the coil and the pair of terminalelectrodes, and a second insulating coating covering at least coil-sideend portions of the pair of bump electrodes in the element body.

In the coil component described above, the insulation between the coiland the element body made of the metal magnetic powder-containing resinis achieved by the first insulating coating. In addition, the insulationbetween the element body and the bump electrode is achieved by thesecond insulating coating. Accordingly, the insulation between theelement body and the bump electrode is improved in the coil componentdescribed above.

In other words, in the coil component 1 according to the embodimentdescribed above, the insulation between the coil 22 and the element body10 made of the metal magnetic powder is achieved by the first insulatingcoating (that is, the first insulator 34, the second insulator 54, andthe protective films 38 and 58). In addition, the insulation between theelement body 10 and the bump electrode 60 is achieved by the insulator62. Accordingly, the insulation between the element body 10 and the bumpelectrode 60 is improved in the coil component 1.

In the coil component according to another aspect, an end portion of thebump electrode on the lower surface side of the element body is exposedfrom the second insulating coating.

In the coil component according to another aspect, the end portion ofthe bump electrode on the lower surface side of the element body is anenlarged portion and a cross-sectional dimension of the enlarged portionin a plane parallel to the lower surface of the element body graduallyincreases toward the lower surface of the element body. Since the lowerend of each bump electrode 60 is the enlarged portion 60 a, the contactarea between the bump electrode 60 and the terminal electrode 70 isincreased. As a result, the bump electrode 60 and the terminal electrode70 can be reliably interconnected.

The bump electrode 60 may extend in the direction orthogonal to thelower surface 10 b of the element body 10 (that is, the thicknessdirection of the substrate 40) or may be inclined with respect to thedirection orthogonal to the lower surface 10 b of the element body 10insofar as the direction intersects with the lower surface 10 b of theelement body 10.

In addition, Japanese Patent No. 6024243 (Patent Document 2) discloses abottom surface terminal-type coil component provided with a substrateextending in parallel to a bottom surface provided with a terminalelectrode, in which coil patterns are formed on both surfaces of thesubstrate. In the coil component, the inside dimension of a coil can beincreased or the number of turns can be increased insofar as the outerperipheral dimension of the coil can be increased while the outer shapedimension of a chip is maintained. As a result, it is possible toimprove coil characteristics such as inductance.

In the bottom surface terminal-type coil component described above, abump electrode extending from an end portion of the coil toward theterminal electrode provided on the bottom surface of the chip hinders anincrease in the outer peripheral dimension of the coil. The inventorshave studied the bump electrode. As a result, the inventors have newlyfound a technique with which coil characteristics can be improved as aresult of an increase in the outer peripheral dimension of the coil.

A coil component according to an aspect of the present disclosureincludes an element body including a magnetic material and having anupper surface and a lower surface parallel to each other, a substratedisposed in the element body and extending in parallel to the upper andlower surfaces, a first coil body disposed in the element body, formedon an upper surface of the substrate, and having a first planar coilhaving a first connection end portion, a first extracting end portion,and a first turn portion interconnecting the first connection endportion and the first extracting end portion and a first insulatorcovering the first planar coil in the same layer as a layer where thefirst planar coil is formed, a second coil body disposed in the elementbody, formed on a lower surface of the substrate, and having a secondplanar coil having a second connection end portion connected to thefirst connection end portion of the first planar coil via the substrate,a second extracting end portion, and a second turn portioninterconnecting the second connection end portion and the secondextracting end portion and a second insulator covering the second planarcoil in the same layer as a layer where the second planar coil isformed, a pair of terminal electrodes provided on the lower surface ofthe element body, and a pair of bump electrodes extending along athickness direction of the substrate and respectively interconnectingthe first and second extracting end portions of the first and secondplanar coils and the pair of terminal electrodes. Each of the pair ofbump electrodes is positioned in a corner portion of a rectangularregion including the first coil body and the second coil body whenviewed from the thickness direction of the substrate. At least an endportion of one of the pair of bump electrodes on the substrate sideoverlaps neither the first turn portion of the first planar coil nor thesecond turn portion of the second planar coil in the thickness directionof the substrate and at least an end portion of the other bump electrodeon the substrate side overlaps neither the first turn portion of thefirst planar coil nor the second turn portion of the second planar coilin the thickness direction of the substrate.

In the coil component described above, the bump electrode is positionedin the corner portion of the rectangular region including the first coilbody and the second coil body, and thus the bump electrode does nothinder an increase in the outer peripheral dimensions of the firstplanar coil and the second planar coil. Accordingly, with the coilcomponent described above, it is possible to improve coilcharacteristics by increasing the outer peripheral dimensions of thefirst planar coil and the second planar coil.

In other words, in the coil component 1 according to the embodimentdescribed above, the bump electrode 60 is within the rectangular region24 including the first coil body and the second coil body and ispositioned in the corner portion of the rectangular region 24 whenviewed from the thickness direction of the substrate 40. Accordingly,when the outer peripheral dimensions of the first planar coil 32 and thesecond planar coil 52 are increased in the range of the rectangularregion 24, the bump electrode 60 does not hinder the increase.Accordingly, with the coil component 1, it is possible to improve coilcharacteristics by increasing the outer peripheral dimensions of thefirst planar coil 32 and the second planar coil 52.

In addition, in the coil component 1, the end portion of the bumpelectrode 60 on the substrate 40 side overlaps neither the first turnportion 32 c nor the second turn portion 52 c. Accordingly, a situationin which the magnetic flux generated in the first planar coil 32 and thesecond planar coil 52 is weakened by the bump electrode 60 issuppressed. In the coil component 1, since a magnetic flux is generatednear the substrate 40 in particular, the coil component 1 can bedesigned such that at least the end portion on the substrate 40 sidedoes not overlap the first turn portion 32 c and the second turn portion52 c.

In the coil component according to another aspect, the rectangularregion circumscribes the first coil body and the second coil body whenviewed from the thickness direction of the substrate.

The coil component according to another aspect further includes a firstisland-shaped electrode provided in an upper surface-side regioncorresponding to a lower surface-side region where the second extractingend portion of the second planar coil is formed and not in contact withthe first planar coil and a second island-shaped electrode provided in alower surface-side region corresponding to an upper surface-side regionwhere the first extracting end portion of the first planar coil isformed and not in contact with the second planar coil.

In the coil component according to another aspect, the bump electrodehas an enlarged portion and a cross-sectional dimension of the enlargedportion in the plane orthogonal to the thickness direction of thesubstrate gradually increases toward the lower surface of the elementbody.

The coil component according to another aspect further includes aconductor connected to at least one of the first planar coil and thesecond planar coil and exposed from the element body.

In the coil component according to another aspect, a cross-sectionalshape of the bump electrode in a plane orthogonal to the thicknessdirection of the substrate is a triangular shape along an outerperiphery of the first turn portion or the second turn portion and twosides defining the corner portion of the rectangular region. Inaddition, in the coil component according to another aspect, the firstextracting end portion and the bump electrode are electricallyinterconnected via a via conductor provided through the region of thesubstrate where the first extracting end portion is formed and across-sectional shape of the via conductor in the plane orthogonal tothe thickness direction of the substrate is a triangular shape along theouter periphery of the first turn portion or the second turn portion andthe two sides defining the corner portion of the rectangular region. Inother words, in the coil component 1, the cross-sectional shape of eachbump electrode 60 in the plane orthogonal to the thickness direction ofthe substrate 40 is a substantially triangular shape along the outerperiphery of the first coil body 30 or the second coil body 50 and twosides defining a corner portion of the rectangular region 24.Accordingly, the bump electrode 60 having a large cross-sectional areacan be realized so as to fit in the corner portion of the rectangularregion 24. Likewise, the first island-shaped electrode 36, the secondisland-shaped electrode 56, and the via conductor 49 also have asubstantially triangular cross-sectional shape along the outer peripheryof the first coil body 30 or the second coil body 50 and two sidesdefining a corner portion of the rectangular region 24, and thus a largecross-sectional area is realized.

In the coil component according to another aspect, a distance betweenthe substrate and the lower surface of the element body is shorter thana distance between the substrate and the upper surface of the elementbody. In other words, in the coil component 1, the distance between thesubstrate 40 and the lower surface 10 b of the element body 10 isshorter than the distance between the substrate 40 and the upper surface10 a of the element body 10. Accordingly, the bump electrode 60 isshorter than in a case where the substrate 40 is at the same distancefrom the upper surface 10 a and the lower surface 10 b of the elementbody 10. It is possible to reduce the direct current resistance in thebump electrode 60 by shortening the bump electrode 60.

The present disclosure is not limited to the embodiments described aboveand can be variously modified. For example, the electronic component isnot limited to a coil component and the electronic component may be acapacitor, a varistor, or the like. In addition, the pattern shapes ofthe first and second coil bodies of the coil portion may be identical toeach other or may be partially different from each other. Further, thedistance between the substrate and the element body lower surface may beequal to the distance between the substrate and the element body uppersurface.

What is claimed is:
 1. A coil component comprising: an element body madeof a metal magnetic powder-containing resin and having a lower surfacefacing a mounting substrate; a coil disposed in the element body andcovered with a first insulating coating; a pair of terminal electrodesprovided on the lower surface of the element body; a pair of bumpelectrodes extending in a direction intersecting with the lower surfaceof the element body and respectively interconnecting both end portionsof the coil and the pair of terminal electrodes; and a second insulatingcoating covering at least end portions of the pair of bump electrodes onthe coil side in the element body.
 2. The coil component according toclaim 1, wherein an end portion of the bump electrode on the lowersurface side of the element body is exposed from the second insulatingcoating.
 3. The coil component according to claim 1, wherein the endportion of the bump electrode on the lower surface side of the elementbody is an enlarged portion and a cross-sectional dimension of theenlarged portion in a plane parallel to the lower surface of the elementbody gradually increases toward the lower surface of the element body.